Glassware annealing lehr having individual modules with self-contained air recirculating means



R. A. FULLER Aug. 26, 1969 GLASSWARE ANNEALING LEHR HAVING INDIVIDUAL MODULES WITH SELF-CONTAINED AIR RECIRCULATING MEANS 4 Sheets-Sheet 1 Filed Nov. 50, 1967 WEET SEYII @EEE mmmQhT' D oom: .60N Dom OOG? QS@ ,mo

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GLASSWARE ANNEALING LEHR HAVING INDIVIDUAL MODULES WITH SELF-CONTAINED AIR RECIRCULATING MEANS Filed Nov. 30, 1967 4 Sheets-Sheet 2 Aug. 26. 1969 R, A. FULLER 3,463,465

GLASSWARE ANNEALING LEHR HAVING INDIVIDUAL MODULES WITH SELF-CONTAINED AIR EECIRCULATING MEANS Filed Nov. 30, 1967 4 Sheets-ShawI 3 FIC3-5 unnunll 'faQ/V Ks' Aug. Z6, 1969 R. A. FULLER 3,463,465

GLSSWARE ANNEALING LEER HAVING INDIVIDUAL MODULES WITH SELFCONTAINED AIR RECIRCULATING MEANS Filed Nov. so, 1967 4 sheets-sheen 4 FIGT/ -T ,35a l 7a United States Patent O ABSTRACT OF THE DISCLOSURE A plurality of tunnel defining lehr units or modules are arranged in end toward end relationship, and an endless conveyor passes through the tunnel for carrying glassware downstream through the tunnel. Each module has a blower in a plenum chamber d ened in its top portion for drawing air upwardly through a central inlet opening into the chamber and for discharging the air downwardly at high velocity through upstream and downstream sets of laterally extending outlet slots. The upstream modules either have burners mounted in their side walls to tire toward the inlet and hence heat the air entering the inlet, or they have heating coils located in the chamber itself. The downstream modules have air intake and exhaust chambers or compartments in their bottom portions, one of these compartments provides cool room air for the inlet of the blower plenum chamber when an associateddamper valve is opened and two other compartments are controlled simultaneously to allow discharge of hot air from the module. Each module has itsrown tempearture responsive control means for operating the burners or the coils and also for operating damper valves in order to maintain a predetermined temperature gradient along the lehr, which gradient can be made to conform to the usual requirements for annealing of glass.

Background of the invention i Prior art recirculating lehrs can be categorized into either one of two general types. The rst type is shown an described in Patent 3,261,596 issued to` Bowman July 19, 1966. The Bowman construction utilizes several independently regulatable zones wherein air is circulated through ducts in the tunnel side walls to a chamber below the conveyor, from which chamber the air rises across the length and breadth of each zone. This lehr construction has the disadvantage that the large exit area associated with the chamber results in very low and non-uniform air velocities, and hence requires that laterally positioned depending batiles be employed to prevent the tunnel air from drifting between adjacent zones. The low air velocity and its associated non-uniformity at all portions of conveyor area in each zone cannot provide ideal conditions for uniform heating or cooling of ware disposed on the conveyor belt, which condition is a prerequisite for ecient, con trollable, and dependable annealing of glassware.

Another lehr construction sometimes referred to as recirculative in type employs external lire boxes, the products of combustion being mixed with recirculated air in externally located fans which return the heated air to the tunnel through ducts. This construction, `and to some extent the Bowman construction also, suffers from the disadvantage of excessive ductwork, with the loss in air moving etiiciency, with the wasted space associated therewith, and with reduced thermal efficiency unless ducts and other external parts of the system are heavily insulated.

Summary of invention This invention relates to glassware annealing lehrs, `and deals more particularly with a lehr having several tunnel 3,463,465 Patented Aug. 26, 1969 ice defining modules, or units, each of which has its own self-contained air circulating means and temperature environmental control for heating or cooling the glassware as it is fed through the lehr in accordance with a predetermined temperature schedule.

A general object of the present invention is to provide a modular glassware annealing lehr wherein heating or cooling air can be discharged downwardly at ahigh velocity from a pressurized plenum chamber in a top portion of each module into the upwardly open glassware, and downwardly around the outside of the ware as it is carried therethrough by a conveyor.

A general object of the present invention is to provide a modular glassware annealinglehr wherein heating or cooling air is discharged downwardly at a high velocity from a pressurized plenum chamber in the tunnel roof, past glassware and through the conveyor into a recirculating chamber where it is turned around for a second pass upwardly through the conveyor and past the glassware after which the air is returned to the plenum chamber.

Another general object of the present invention is to provide a modular glassware annealing lehr wherein heating or cooling air is discharged downwardly at a high velocity through two sets of laterally extending outlet slots arranged adjacent the upstream and downstream ends, respectively, of each module whereby uniform heating or cooling is attained across the width of the convyeor at two distinct zones in each lehr module.

Still another general object of the present invention is to provide a modular glassware annealing lehr of the foregoing character wherein the downwardly discharged air is used to provide a high velocity air curtain at the upstream and downstream boundaries of each lehr module to prevent air controlled at a given temperature in one module from passing into an adjacent module in which the air is being controlled at a diferent temperature.

Another object of the present invention is to prevent the tendency of the cooler air at the downstream end of the lehr tunnel from drifting upstream toward the heating section.

A further general object of the present invention is to provide a modular glassware annealing lehr wherein in each module the heating or cooling air is returned to a plenum chamber inlet from a chamber provided -beneath the conveyor for this purpose.

A still further object of the present invention is to provide a modular glassware annealing lehr wherein the downstream, or cooling air modules, are designed either to recirculate tunnel air, or to introduce cooler air into the recirculating cycle and simultaneously to exhaust air which has been heated by extracting heat from the glassware.

' Brief description of the drawings FIG. 1 is an elevational view of a lehr having individual modules, with temperature repsonsive control systems for each module being schematically shown.

FIG. 2 is a` graphical presentation of the glassware temperature at each point throughout the length of a lehr of the type shown in FIG. l.

FIG. 3 is a plan view of two adjacent lehr modules, being taken on the line 3-3 of FIG. l.

FIG. 4 is a vertical sectional view of the two modules shown in FIG. 3, being taken on the line 4--4 of that figure.

FIG. 5 is a vertical sectional view of a burner equipped module taken on the line 5--5 of FIG. 4.

FIG. 6 is a vertical sectional view of a ware cooling module taken on the line 6--6 of FIG. 4.

FIG. 7 is a view similar to FIG. 4 of an alternative embodiment for this module showing alternative heating means for the recirculating air in the modules.

FIG. 8 is a vertical sectional view of the module shown in FIG. 7, being taken on the line 8 8 of that figure.

Detailed description of the annealing process In glassware annealing lehrs, the first step in the annealing process usually involves heating of the ware above its annealing temperature (defined as that temperature corresponding generally to the upper end of the annealing range) so that strain is released and the ware can be cooled subsequently at a controlled rate, as depicted in FIG. 2, according to a schedule which is most conducive to minimum lehr length but within the requirements of good commercial annealing. In most cases heat is required in the heating section, although portions of the ware often are hotter than necessary. The heating section must equalize the ware effectively at a temperature above the annealing point of the glass to relieve the strain substantially. Rapid and intensive movement of air which has been heated above the final desired temperature of the glass will reheat the cool portions of the ware and equalize the hotter portions by convective heat transfer. The more intense the rate of recirculation of the air, the more rapidly the equalization of ware temperature will be accomplished. A lower temperature differential between air and glass can be maintained when the rate of recirculation is great, and temperature control of the glass can be obtained with higher precision.

As the glassware leaves the heating section of the lehr, its temperature is reduced through the annealing range, or more specifically from a temperature somewhat above its annealing point to a temperature somewhat below its strain point (defined as that temperature from which the ware may be cooled rapidly without the introduction of objectionable permanent strain). Heat may be added in the annealing section when required, but normally heat is removed at a controlled rate as indicated by FIG. 2.

It can be seen from FIG. 2 that a rapid reduction in temperature is possible once the glassware leaves the annealing section of the lehr. More particularly, the recirculated cooling section of the lehr serves to reduce the temperature of the ware from approximately its strain point to that temperature at which Ware can be discharged from the tunnel and exposed to ambient temperature outside of the lehr without danger of thermal shock. Finally, forced cooling is used for reducing the ware to a temperature at or near room temperature where it can be handled conveniently.

General description of the recirculating lehr The present invention provides modular lehr units for the heating, annealing, and recirculating cooling sections of the lehr, which modules can be selected and jointed together to construct a lehr having a length and configuration which will satisfactorily heat, anneal, and cool the glassware for which the lehr is intended. As so arran-ged the modules dene an elongated tunnel `for receiving the upper run of an endless conveyor of the open mesh belt type commonly used in annealing lehrs. The lower run 20a of the conveyor travels in the opposite direction between the underside of the modules and the oor, as shown. As is common practice, the drive mechanism for the conveyor belt is provided at the discharge end of the annealing lehr as indicated generally at 22 in FIG. l. Finally, and still with reference to the conveyor, small heating units 23, 23 are provided adjacent the entrance end of the upper run of the conveyor for heating the belt prior to entry into the heating section of the lehr.

Turning now to FIG. 1 in greater detail, the heating section of the lehr can be seen to comprise a single module similar to the modules`used in the annealing section of the lehr. However, since heat usually will be required in the heating section module the burner 10 is supplied with fuel at a controlled rate to raise the temperature of the glassware entering the lehr to a point at, or slightly above, the annealing temperature as depicted in FIG. 2.

In the embodiment shown in FIG. 1, the annealing section comprises three identical modules arranged in end toward end relationship downstream of the heating section module. The modules comprising the annealing section of the lehr are equipped with burners also, as indicated at I2, 12 and suitable temperature responsive control systems are provided as indicated for controlling the fuel flow to these burners so that heat is provided when needed. When cooling is required the fuel is shut off automatically and air only is introduced through the unit 12.

The recirculated cooling section of the lehr comprises three cooling modules which also are arranged in end toward end relationship with one another and with the burner equipped module furthest downstream in the annealing section. The forced cooling section of the lehr, and the drive section thereof comprise conventional components and need not be described in detail herein.

Detailed description of lehr modules Turning now to a more detailed description of the individual lehr units or modules, FIG. 3 shows, in plan view, the downstream burner equipped module 14 and the upstream cooling module 16 are attached to one another in end toward end relationship by vertically arranged angle brackets 18, :1S which also serve as legs for supporting the modules above the floor as shown in FIG. 4.

The burner equipped lehr module 14, as well as the cooling air module 16, each define a plenum chamber 2-4 in their respective top portions, and each plenum chamber is provided with a centrifugal type blower 26 for drawing air upwardly through an inlet opening 28 defined inthe lower wall of the plenum chamber 24. ln the case of the burner equipped lmodule 14 the air will have been heated as a result of operation of the burners 12, 12 which fire into the lehr above the conveyor 20 and generally toward the inlet opening 28 as best shown in FIG. 5. In the case of the cooling lehr module 16, the air drawn into the inlet 28 is not so heated and may be air which is recirculated within that particular lehr module in a Imanner to be described. Each centrifugal blower 26 is arranged on a vertically disposed axis generally centered above the circular inlet opening 28, and means is provided for driving the shaft so that the blower moves air into the plenum chamber thereby pressurizing the same. As shown, the means for driving the blower comprises individual electric motors 30, 30 drivingly connected to the upright shafts associated with the blowers 26, 26 respectively.

Two sets of laterally extending outlet slots 25 and 27 are provided in the lower wall of each plenum chamber 24 and it is a feature of the present invention that the air discharged through these slots provides two longitudinally spaced patterns, or curtains, of high velocity discharge air, each of which extends completely across the tunnel adjacent the upstream and downstream ends of each lehr module respecti-vely. Thus, the discharged air travels downwardly around the outer surfaces of the individual glassware articles, and also into the open tops thereof, and ultimately passes downwardly through the conveyor 20 into a recirculating chamber delined in the bottom portion of each module. In the case of the burner equipped module 14 the chamber comprises a single compartment 31, with two piers 32 as shown in FIG. 5 for supporting the belt frame for the conveyor 20. The warm air discharged downwardly past the ware B from each set of outlet slots passes through the conveyor and thence upwardly through the conveyor for a second pass at the ware prior to being drawn into the inlet opening by the `blower 26 and recirculated through the plenum chamber 24 in a closed cycle of operation.

Means is provided in each lehr ymodule for controlling the temperature therein according to the schedule depicted in FIG. 2. A thermocouple 34 is provided in each burner equipped module14, as shown inFIG. 5, which thermocouple 34 is connected to a temperature responsive control unit 36 mounted at thetop of the module, as shown in FIG. 1. The unit 36 operates a controller 38 which regulates a valve 40 in the fuel line to the burner 12. Air to the burner 12 is preset initially by a valve 42 and it is a feature of the present invention that air in excess of that required for combustionis provided continuously by the blower 44 for cooling purposes in the annealing section. When heat is required fuel is supplied to the burner automatically in response to the temperature controller 36, but normally the temperature of ware conveyed through the 'annealing section is Areduced as depicted in FIG. 2.

Turning now toa more detailed description of the air cooling lehr modules 16, 16 whichcomprise `the recirculated cooling section of the lehr shown in FIG. 1, FIG. 4 shows such a unit as also including a plenum cham-ber 24 defined in the Iupper portion of .the module and provided with -a centrifugal blower 26 driven by an associated electricmotor 30 throughldrive` means similar to that shown in the burner equipped module .discussed above. The plenum chamber 24 is provided with two sets of laterally extending outlet slots 25 and 27 which provide two longitudinally spaced patterns or curtains of high velocity discharge air which extend 'completely across the tunnel and emanate at `a high velocity from the plenum chamber 24 downwardly onto the ware B being conveyed through the individual cooling section lehr modules. The chambers associated with.the cooling modules 16, 16 can be seen from FIG. 4 to comprise three laterally extending compartments 50, 52 and 54 all of which are upwardly open and communicate with fa small common chamber 33 defined between the upper boundaries of said three compartments and the lower surface of the belt 20. Two of the compartments 50 and -52 are disposed below the laterally extending slots 25 and 27 respectively adjacent the upstream and downstream ends of the module 16 for receiving the downwardly discharged air. The third compartment 54 is arranged below the plenum chamber inlet opening 28 so that the blower 26 can draw air upwardly from the compartment S4, when damper Nalves 56, 56 in the opposite ends thereof are opened as shown in FIG. 6. As shown in FIG. 1, damper valves 58, 58 are provided for the upstream and downstream compartments 50 and S2 for exhausting warm air therefrom when cool room air is drawn into the circulating cycle through the damper valves 56, 56 associated with the center compartment 54. As shown in FIG. l the damper valves 56 and 58 are connected to one another for movement in unison to permit discharge of heated air and thereby avoid pressurizing the interior of the lehr. A thermocouple 34 having an elongated probe is provided in the cooling lehr module for sensing the temperature of the air therein. The signal from the thermocouple 34 is sent to a temperature control unit 60 provided on the upper surface of the module 16 to provide a mechanical motion in response to the temperature sensed by the thermocouple 34. As best shown in PIG. 3, the temperature control unit 60 is connected mechanically to the damper 'valves 56, 56 associated with opposite ends of the central compartment `54 through a link 62 and cables 64 and `66. Thus, the damper valves 56 'and 58 are adapted to be opened or closed automatically in response to corresponding variations of the temperature sensed in the lehr module by the thermocouple 34.

Turning now to a description of the alternative embodiment for the heating section modules depicted in FIGS. 7 and 8, the module itself will be seen to comprise a substantially identical structure 14a having a plenum cha-mber 24a defined in its top portion and a recirculating chamber 31a below the conveyor 20. A centrifugal blower 26 draws air into the chamber 24a through an inlet opening 28a, and electrically energized heating coils 70, 70 in the chamber 24a heat the air therein prior to emanation of the air through the two longitudinally spaced sets of outlet slots 25a and 27a. These coils 70, 70 are accessible from outside the lehr, being removable through a tubular housing 72 in the tunnel side wall. A thermocouple 34 senses air temperature in the lehr module and is connectedto a control unit 74 for energizing the coilsl to maintain a predetermined temperature when recirculating air temperature is below the control setting. Air nozzles 76, 76 are provided in the tunnnel side walls for introducing cooling air when the temperature is higher than the desired temperature depicted in FIG. 2. An air valve 78 is controlled :by the unit 74 for this purpose.

I claim:

1. A glassware annealing lehr comprising a plurality of tunnel defining modules connected to one another in end-toward-end relationship, an endless conveyor having an upper run extending through the tunnel so formed, each of said modules having a bottom portion which defines an air circulating chamber below said conveyor upper run, each of said modules having a top portion which defines a plenum chamber with a central inlet opening and with outlet slots adjacent the upstream and downstream ends of said module, and air moving means` in each of said plenum chambers for drawing air upwardly through said inlet opening and for discharging the same air downwardly at a high velocity out of said outlet slots through said conveyor upper run into said circulating chamber.

2. A glassware annealing lehr as set forth in claim 1 wherein at least one of said modules includes burners adapted to tire into the tunnel above the conveyor and between said upstream and downstream outlet slots generally toward said inlet opening whereby the air drawn into said inlet by said air moving means is mixed with products of combustion and heated prior to being discharged downwardly toward said conveyor upper run.

3. A glassware annealing lehr comprising a plurality of tunnel dening modules connected to one another in end-toward-end relationship, an endless conveyor having an upper run extending through the tunnel so formed, each of said modules having a bottom portion which detines an air circulating chamber below said conveyor upper run, each of said modules having a top portion which denes a plenum chamber with a central inlet opening and with outlet slots adjacent the upstream and downstream ends of said module, air moving means in each of said plenum chambers for drawing air upwardly through said inlet opening and for discharging the same air downwardly at a high velocity out of said outlet through said conveyor upper run into said circulating chamber, at least one of said modules has an air circulating chamber which includes three laterally extending compartments, two of said compartments being upwardly open and arranged below said outlet slots adjacent the upstream and downstream ends of said module for receiving said downwardly discharged air, said third compartment also being upwardly open and arranged below said plenum chamber inlet opening.

4. A glassware annealing lehr as set forth in claim 3 wherein said third compartment is further characterized by at least one damper valve which can be opened to admit relatively cool room air therein, and damper valves associated with said upstream and downstream compartments for exhausting warm air therefrom as cool room air is drawn into the circulating cycle through said damper valve in said third compartment.

5. A glassware annealing lehr as set forth in claim 4 wherein at least one of said modules includes burners adapted to tire into the tunnel above the conveyor and between said upstream and downstream outlet slots generally toward said inlet opening whereby the air drawn into said inlet by said air moving means is mixed with products of combustion and heated prior to being discharged downwardly toward said conveyor upper run.

6. A glassware annealing lehr as set forth in claim 5 and further characterized by temperature responsive control means in each of said modules having burners for operating said burners to maintain a predetermined temperature suitable for annealing glassware.

7. A glassware annealing lehr as set forth in claim 6 and @further characterized by temperature responsive control means in each of said modules having a three compartment room air circulating chamber, said last-mentioned means serving to operate said damper valves to reduce the glass temperature at a controlled rate.

8. A glassware annealing lehr as set forth in claim 7 wherein at least two burner equipped modules are provided in end-toward-end relationship and comprise the annealing section of the lehr, each of said burner equipped units having self-contained temperature responsive control means for said burners to maintain a predetermined temperature in said annealing section.

9. A glassware annealing lehr as set forth in claim 8 wherein at least two room air circulating modules are provided in end-toward-end relationship to provide a circulative cooling section downstream of said annealing section of said lehr, each of said room air circulative modules having self-contained temperature responsive control means for said damper valves to reduce the glass temperature at a controlled rate.

10. A glassware annealing lehr as set forth in claim 9 wherein said air moving means in each of said modules comprises a continuously driven centrifugal blower rotating on a vertically disposed axis which is centered over said inlet and in said plenum chamber so that each plenum chamber is pressurized with air drawn through said inlet opening in order to provide a high velocity of discharged air at said outlet slots.

11. A glassware annealing lehr comprising a plurality of tunnel dening modules connected to one another in end-toward-end relationship, an endless conveyor having an upper run extending through the tunnel so formed, each of said modules having a bottom portion which denes an air circulating chamber below said conveyor upper run, each of said modules having a top portion which denes a plenum chamber with a central inlet opening and with outlet slots adjacent the upstream and downstream ends of said module, air moving means in each of said plenum chambers for drawing air upwardly through said inlet opening and for discharging the same air downwardly at a high velocity out of said outlet slots through said conveyor upper run into said circulating chamber, and at least one of said heated modules includes electrically energized heating coils in plenum chamber for heating the air before it is discharged at a high velocity through said outlet slots.

12. A glassware annealing lehr as set forth in claim 11 and further characterized by means for introducing air between said upstream and downstream slots generally toward said inlet opening, and temperature responsive control means in each of said coil equipped modules for controlling the temperature in said annealing section.

References Cited UNITED STATES PATENTS 2,677,336 5/1954 Spooner 236-8 X 3,261,596 7/1966 Bowman 263--8 3,347,182 10/1967 Royer 263-8 X JOHN J. CAMBY, Primary Examiner 

